Polymer filaments having profiled cross-section

ABSTRACT

The invention provides a profiled polymer filament having an open hollow cross-sectional shape normal to the longitudinal axis of the filament, wherein the cross-section is dimensioned to prevent the filament from interlocking with a second filament of the same cross-section. The invention also provides methods of manufacture of such filaments by melt spinning a polyamide, and spinnerets suitable for use in melt spinning such filaments.

FIELD OF THE INVENTION

This invention relates to synthetic polymer filaments with an “openhollow” profiled cross section normal to the longitudinal axis of thefilament. The invention further relates to spinneret plates for meltextrusion of the filaments, and to methods of manufacture of thefilaments by melt extrusion.

BACKGROUND

Textile fibres or filaments from synthetic polymers, particularlypolyamide polymers like nylon 66 and nylon 6, and multifilament yarnsmelt extruded from the same polyamide polymers, are produced for appareluses typically as partially oriented yarn (POY) and drawn yarn. POY willhave an elongation to break greater than about 55% and drawn yarn willhave a lower elongation. Circular is the most common cross sectionalshape for each filament comprising the multifilament yarns of eithertype, e.g. POY and drawn yarn. Variation on the individual filamentcross sectional shapes include trilobed or 6-lobed, disclosed inJapanese Kokoku patent document 01-20243 (Nihon Ester KK), the scallopedoval cross section as disclosed by in U.S. Pat. No. 5,834,119 (Roop) andhollow polyamide filaments with a single longitudinal void, disclosed inU.S. Pat. No. 5,604,036 (Bennett et al.).

All of the foregoing examples are known variants of profiled crosssectional shaped POY and drawn yarn. Filaments with cross sectionalshapes other than circular provide multifilament yarns for fabrics andgarments with varied visual aesthetics, opacity and cover and lighterweight. Yarns from hollow filaments, for example the yarns of the lastmentioned United States patent; provide lighter weight fabrics andgarments and enhanced heat retentive properties versus conventionalcircular filaments, without a longitudinal void. Hollow filament yarnsare particularly suited for apparel applications when textured by theconventional processes, e.g. air jet texturing (AJT) and false twisttexturizing (FTT) to obtain bulky yarns. Hollow flat yarns for directuse in weaving applications are also known.

Both partially oriented and flat nylon yarns in a high void volumehollow are disclosed by Bennett et al. However, filaments withlongitudinal voids are difficult to close perfectly at spinning, and mayalso deform substantially during the texturing process. This may resultin a letter ‘C-shaped’ filaments and/or collapsed tube cross sectionalshapes. Letter C-shaped filaments are able to pack closely together witha loss of open space among neighbouring filaments. In addition, letterC-shaped cross sectional filaments and collapsed tube cross sectionslead to undesirable yarn and fabric properties as a result of suchoccurrences. Increased fabric density and diminished heat retention ofthe fabric and garments are among the undesirable properties.Furthermore, yarns from filaments with varied amounts of rupturedlongitudinal voids contribute to dyed fabric streakiness and the intactfilament voids provide opportunistic bacteria with a place to flourish.

It has now been found that the above-enumerated disadvantages can beovercome by the production of polymer filaments having a novelcross-section.

The present invention provides a profiled filament from syntheticpolymer having an “open hollow” cross-sectional shape normal to thelongitudinal axis of the filament. The cross-section is dimensioned toprevent a first filament from interlocking with a second filament havingthe same cross-section. This means a region proximate to each tip of thecross-section is wider than a spacing between said regions defining anopening to the open hollow cross-section.

The profiled cross sectional shape filaments of the invention areprovided by the novel shape and design of the extrusion capillary. Thefilaments of this invention are prepared directly by melt extrusion ofsynthetic polymer through a multi-capillary spinneret plate. The term“open hollow” denotes a generally C-shaped or U-shaped cross-sectionhaving a hollow center, and a solid region defining wall portionextending around the hollow center to enclose the hollow center, butwith an opening in one side of the wall linking the center to theoutside of the filament. The opening is narrower than the diameter ofthe hollow center, thereby forming a throat or constriction between thehollow center and the outside of the filament.

Preferably, the filament comprises a solid part substantially enclosinga central hollow region. An opening leads from the exterior of thefilament into the central hollow region. The solid part includes legsthat terminate in feet. Confronting surfaces of the feet define thethroat (the narrowest dimension) of the opening. The throat of theopening subtends a radial angle alpha (□) of not more than 90°, morepreferably not more than 75° and most preferably from 10° to 60°. Asseen in FIG. 1, the radial angle alpha (□) is that angle defined betweentwo rays R₁ and R₂ originating at a point C. The point C is that pointlying on the interior surface of the solid part of the filament thatlies farthest from a reference line R₃ tangentially connecting the tipsof the feet. Each ray R₁, R₂ extends from the point C and lies tangentto a point on the confronting surfaces of the feet defining the throatof the opening D. The solid part subtends a radial angle equal to 360°minus angle alpha (360°-□). Preferably, the solid part of thecross-section subtends a radial angle of at least 270°. More preferablythe solid part subtends a radial angle of at least 300°.

The filaments according to the present invention are adapted to preventinter-engagement or stacking of the filaments. For example, hook-likeengagement of two cross sections arising from insertion of an end of thesolid part of a first filament cross-section through the opening in thecross-section of a second filament is prevented. This provision can beachieved as already described, by making the solid portion of thecross-section subtend a large radial angle, whereby the opening in thefilament cross-section is very small. Alternatively or additionally, theends of the solid part of the cross section may be enlarged to inhibitinsertion into the opening of other filaments.

The solid portion of the cross-section in the filaments according to thepresent invention may form a single continuous curve. Preferably, thecross-section comprises a “central arcuate” or base portion having firstand second ends and two side or “leg” portions. The leg portionsextending in substantially side-by-side relationship from the first andsecond ends of the central arcuate portion.

In preferred embodiments, such as the filament cross section geometryshown in FIG. 1, the filament cross sectional shape is characterized bya central arcuate portion 1 (extending horizontally in FIG. 1) and firstand second, generally parallel, elongated leg portions 2,3 (extendingvertically in FIG. 1) joined to the central arcuate portion. The distalportion of each leg (2,3) opposite the juncture with the central arcuateportion 1 defines an enlarged foot portion 4. Each foot portion 4 ischaracterized by dimension F, the length of the foot, as shown inFIG. 1. The profiled filament cross-section is open in the center. Thisopen portion is bounded on three sides by the leg portions 2,3 andcentral arcuate base portion 1. The feet portions 4 are oriented in asubstantially side-by-side relationship defining an aperture betweenconfronting surfaces of the foot portions with dimension D leading tothe open portion, as shown in FIG. 1. The dimension D is less thandimension F. As a result, any foot on any leg of the profiled filamentis sufficiently large with respect to the aperture between the pair oflegs on any other identical filament to prevent a foot of the firstfilament from being accommodated (interlocked) between the legs of theother filament in a multifilament yarn bundle, as illustrated by FIG. 2.

Preferably, the polymer used to form the profiled polymer filamentaccording to the present invention is a polyamide. More preferably, thepolyamide polymer has a relative viscosity, by a formic acid method,greater than 40, and still more preferably the relative viscosity of thepolyamide by a formic acid method is in the range of 46 to 56.Preferably, the polyamide is selected from the group consisting of nylon66 and nylon 6 and copolyamides.

Preferably, the single filament linear density is from 0.5 to 20 dtex,and more preferably it is from 2 to 10 dtex. Most preferably it is lessthan 4 dtex. Preferably, the filament cross-sectional shape issubstantially constant along the length of the filament. Preferably, thefilament non-uniformity is less than 1 Uster %.

The profiled filaments according to the present invention provide alighter unit weight yarn, particularly after texturing by AJT (air jettexturizing) or FTT (false twist texturizing). The yarn incorporateshigh free volume of air space. The volume of air space contributes toenhanced thermal retention of fabrics and garments produced from theyarn. The yarn when knitted or woven into fabrics provides a less densefabric than similarly constructed fabrics from solely circular crosssection filaments. Furthermore, the yarn exhibits a high moisturewicking capacity.

Accordingly, the present invention further provides a multifilament yarncomprising at least a portion of the profiled filaments according to thepresent invention.

Preferably, the yarn comprises at least 10% by weight of the profiledfilaments according to the present invention, more preferably at least25% of such filaments, still more preferably at least 50% of suchfilaments and most preferably it consists essentially of such filaments.

The present invention further provides an article comprising at least aportion of the yarn according to the present invention. Preferably, thearticle comprises a textile fabric that is knitted or woven from a yarnaccording to the present invention.

A further aspect of the present invention is a spinneret for theproduction of the profiled open hollow filaments according to thepresent invention by melt extrusion of polymer into filaments. Thespinneret comprises a plate having upper and lower surfaces connected byan assembly of capillaries. The shape, size and configuration of thecapillaries are adapted to the melt spinning of filaments according tothe present invention. Specifically, either each capillary comprises twoadjacent segments as in FIG. 3 a, whereby the open hollow filament crosssection longitudinal to the axis of the filament is obtained as themolten polymer streams from each segment coalesce at a point between thesegments or each capillary has an open hollow transverse cross-sectionas in FIG. 3 b.

The preferred spinneret plate for the production of the profiled openhollow filaments is one with each capillary comprised of two segments inFIG. 3 a. Each segment is comprised of a straight length portion 30having at each end a junction with a pair of projecting portions. At thefirst end, the pair of projecting portions are of equal area and eachcomprise a straight portion 31,32 terminating in a round portion 33,34.At the second (opposite the first) end, are a pair of unequal areaprojecting portions. The first unequal area projecting portion iscomprised of straight portion 35 and round portion 36 and the secondunequal area projecting portion is comprised of straight portion 37 andround portion 38. Therefore, each segment of the capillary has threeequivalent projecting portions, two on one end and one on the oppositeend. The unique (longer) projecting portion present on each segment iscomprised of straight portion 37 and round portion 38. Preferably, eachcapillary segment is the mirror image of the other segment. Morepreferably, each segment is the nonsuperimposable mirror image of theother segment, for example as illustrated by FIG. 3 a. Thenonsuperimposable mirror image relationship means that each segmentpossesses handedness in the same way as do human left and right hands.

The open hollow filament cross section normal to the longitudinal axisof the filament is obtained as the molten thermoplastic polymer streamsfrom each capillary segment coalesce at a point between projectingportions of the two segments. That is, the open hollow filament crosssection of the invention is formed as the molten polymer streamcoalesces between confronting round portions 38 of the left and rightcapillary segments shown in FIG. 3 a.

In the case where the capillaries themselves have an open hollowcross-section, the capillary illustrated by FIG. 3 b is a preferredspinneret geometry cross section for the production of profiled openhollow filaments. Each capillary has a cross sectional shape comprisinga first straight portion 40 with a first end and a second end, oppositeeach other. Bifurcating from the first end of the first straight portion40 are a second straight portion 48 and a third straight portion 50. Thesecond straight portion 48 terminates in a round portion 49 and thethird straight portion 50 extends to a point of bifurcation; wherein afourth straight portion 53 and a fifth straight portion 52 extend fromthis point of bifurcation. The fourth and fifth straight portions havingunequal areas and each terminate in round portions 54 and 51. Similarly,bifurcating from the second end of the first straight portion are asixth straight portion 41 and a seventh straight portion 43. The sixthstraight portion 41 terminates in a round portion 42 and the seventhstraight portion 43 extends to a point of bifurcation; wherein an eighthstraight portion 46 and a ninth straight portion 44 extend from saidpoint of bifurcation, the eighth and ninth straight portions havingunequal areas and each terminate in round portions 45 and 47.

In a further aspect, the invention provides a process for making drawnyarns and partially oriented yarns (POY) with a modified filament crosssection according to the present invention. Generally, the processcomprises extruding a polyamide melt, typically nylon 66 or nylon 6, of40 to 60 RV (measured in formic acid), and preferably 48 to 52 RV toform a plurality of filaments. The spinneret according to the inventionis maintained at a temperature selected from the range 245 to 295° C.,more preferably it is 280° C. Multiple filaments extruded through thespinneret are cooled in a cross flow of air to form solid filaments.These filaments may be treated with oil, converged, interlaced anddrawn, or remain undrawn, prior to winding up a multifilament yarn at aspeed greater than 3000 meters per minute (m/min).

Referring now to the process schematic in FIG. 5, a drawn yarn isprepared by following path A. The melted polymer 10, a polyamide, ispumped to the spin pack 20 and forced throught spinneret plate 30 toform filaments 40. The emerging filaments are cooled by a cross flow ofair 50, having an air velocity of about 0.15 to 0.5 meters per minute.The cooled filaments are converged into a yarn 60, and an oil and waterfinish is preferably applied to the resulting yarn bundle at 70. Theyarn 60 is forwarded through a first air interlace jet 80 to becomeintermingled yarn 90. Yarn 90 is forwarded to a first godet 92 (the feedroll) and its associated separator roll, wrapping several times toprevent slippage, and then to a second godet 94 (the draw roll) and itsassociated separator roll. The draw roll 94 is moving at a surface speedof 60 to 100%, preferably 80%, greater than that of the feed roll 92.The yarn bundle is thereby drawn (elongated), preferably by a totalfactor of about 1.8, reducing the overall yarn titer to form yarn 100.The drawn yarn 100 is preferably treated by a relaxation device 110 toset the draw and to relax the yarn as is conventionally practised in theart. Any known relaxation device may be employed, including steam,heated fluid, hot tube, hot shoe, heated rolls. The relaxed yarn bundle120 is optionally passed through a second interlace jet 130 andoptionally oiled before the relaxed yarn 140 is wound up on a tube 150at a winding speed greater than 3000 meters per minute, more preferablyabout 3800 meters per minute. The resulting drawn yarn has an elongationof 25 to 45%, preferably 40 to 45%, and a tenacity of 35 to 45 cN/tex.

Alternatively, referring now to the process schematic in FIG. 5, apartially oriented yarn (POY) is prepared by following path B. Themelted polymer 10, a polyamide, is pumped to the spin pack 20 and forcedthrough spinneret plate 30 to form filaments 40. The emerging filamentsare cooled by a cross flow of air 50, having an air velocity of about0.15 to 0.5 meters per minute. The cooled filaments are converged into ayarn 60, and an oil and water finish is preferably applied to theresulting yarn bundle at 70. The yarn 60 is forwarded through a steamatmosphere containing interfloor tube 75, as is known in the art. Thesteam treated yarn 85 is intermingled at 80 partially wrapped aroundgodet 82 and godet 84, which control any variations in winding tensionthe yarn may experience. The yarn 115 is wound up as a package of yarnon tube 160 at a speed of about 3800 meters per minute. The POY producedpreferably has an elongation of 55 to 85%, preferably 75%, and atenacity of 25 to 40 cN/tex, preferably about 30 cN/tex.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 shows a cross section normal to the longitudinal axis of thefilament through one filament with the preferred cross sectional shapeshowing the dimensions R, F and D, rays R1, R2, reference point C,tangent reference line R3 and the angle alpha (□);

FIG. 2 shows a cross section normal to the longitudinal axis of thefilaments through two adjacent filaments according to the invention;

FIG. 3 a is a plan view (to scale) of a two-segment spinneret capillarycross sectional shape according to the present invention;

FIG. 3 b is a plan view (to scale) of a one-segment spinneret capillarycross sectional shape according to the present invention;

FIG. 4 a is a yarn bundle photomicrograph of a yarn cross sectioncontaining 26 filaments produced by melt spinning in accordance with thepresent invention from the spinneret capillary cross sectional shapeFIG. 3 a.

FIG. 4 b is a yarn bundle photomicrograph of a yarn cross sectioncontaining 26 filaments produced by melt spinning in accordance with thepresent invention from the spinneret capillary cross sectional shapeFIG. 3 b.

FIG. 5 is a schematic of the apparatus for carrying out the fully drawnyarn (A) and the POY (B) spinning processes according to the presentinvention.

Test Methods

Water Wicking Test Method: The principle of the method involvessuspending a strip of fabric vertically with its lower end immersed inwater. The height to which the water rises up the fabric in measured atfixed time intervals. The fabric samples taken are 300 mm long and 25 mmwide. The samples are conditioned at a relative humidity of 85% +/−5%and 20° C.+/−2° C. for 16 hours. The maximum rise height of the 20°C.+/−2° C. water is measured after two minutes. The height is measuredfrom the surface of the water to the point on the fabric of maximumwater rise. The mean value of three measurements is reported for eachperpendicular fabric direction.

Fabric Thickness Test Method: The fabric thickness is the mean distancebetween upper and lower surfaces of the material measured under aspecified pressure. The fabric samples are conditioned as for waterwicking. The measuring apparatus used is a Shirley Thickness Gauge with50 cm2 presser foot. The pressure foot is allowed to fall under its ownmomentum onto the fabric. The measurement is repeated ten times and themean and standard deviation are reported to the nearest 0.05 mm.

EXAMPLES Example 1

A first multifilament yarn (Yarn 1A) of 96 dtex and 26 filaments wasspun as a POY using the apparatus shown schematically in FIG. 5 and aspinneret plate with two segment capillaries according to FIG. 3 a.

Nylon 66 polymer chip of 49.4 RV, by the formic acid method, was melted10 and extruded through a filter pack 20 and through a spinneret plate30 with 26 capillaries of the segmented cross sectional shape shown inFIG. 3 a at a spinneret temperature of 280° C.

Next, the emerging filaments 40 were cooled by a cross flow of air 50,with an air velocity of 0.45 meters per minute. The quench air wasdirected, with reference to FIG. 3 a, so as to first encounterconfronting lobes 38 of the two segment capillary. The cooled filaments60 were converged into a yarn at 70 where an oil and water finish wasapplied to the resulting yarn bundle. The converged yarn with the finishapplied was forwarded along Path B in FIG. 5. The yarn was passedthrough a steam atmosphere containing interfloor tube 75. The steamtreated yarn 85 was intermingled with apparatus 80. The intermingledyarn 115 was wound up as a package of yarn on tube 160 at a speed of3800 meters per minute.

The POY produced in this way has a yarn linear density of 96 decitex, anelongation to break of about 75% and a tenacity of 30 cN/tex. The crosssection of the yarn is shown in FIG. 4 a.

A second multifilament partially oriented yarn (Yarn 1B) of 96 dtex and26 filaments was spun exactly as the first POY using the apparatus shownschematically in FIG. 5. For Yarn 1B a spinneret plate with capillariesaccording to FIG. 3 b was used. The elongation and tenacity propertieswere the same as for the first POY. The cross section of the Yarn 1B isshown in FIG. 4 b.

A comparative multifilament yarn (Yarn 1C) of 96 dtex and 26 filamentswas spun in exactly the same way as the first yarn, except for replacingthe spinneret plate with one having 26 “circular cross sectional” shapedcapillaries.

All samples, 1A and 1B (yarns of the invention) and 1C (a circular crosssection comparative yarn) were separately 8-plied and then air jettextured (AJT) using a HEBERLEIN HEMAJET (Registered Trade Mark) to makea 730 decitex by 208 filament (8×26 filaments) textured yarn. Thesetextured yarns were 2-plied and knitted into a “full cardigan structure”and tested for thermal transmittance.

The thermal transmittance test method was essentially that of ASTMD1518-85 (as reapproved 1990). This method measures the time rate ofheat transfer from a warm, dry, constant-temperature, horizontalflat-plate up through a layer of the knitted cardigan test material to arelatively calm, cool atmosphere. Thermal resistance was measured andthe thermal insulation or CLO value calculated. The “CLO” is a unit of“clothing thermal resistance” in ASTM D1518 and equal to 0.155 (° C.m2W-1). The base temperature was 25° C. (T1) and the head plate,temperature was 35° C. (T2). There was minimal pressure applied to thecardigan knit, 260 Nm-2 during the test procedure. Each sample wastested three times to give the mean result reported in Table 1 below.

These test results, reported in Table 1, show a 13-15% increase inthermal resistance for the preferred open hollow cross section versusthe circular cross section yarn in a knit construction. Similarly, theCLO values for the open hollow cross section versus the circular crosssection yarn in a knit construction increased by 13-15%. Clearly, theopen hollow filament yarn in the knit construction tested is a betterthermal insulator versus the circular filament yarn. TABLE 1 Thermal CLOvalue resistance Meter² ° C. Meter² ° C. W⁻¹/(0.155) Yarn used incardigan knit W⁻¹ × (10³) ASTM D1518-85 Yarn 1A (2 × 730f208) 103.7 0.67invention cross section using two segment spinneret Yarn 1B (2 ×730f208) 105.0 0.68 invention cross section using one segment spinneretYarn 1C (2 × 730f208) 91.5 0.59 “circular” cross section

Example 2

POY samples from Example 1, Yarn 1A and comparative Yarn 1C, both 96decitex and 26 filaments as spun, were false-twist textured (FTT) at 600meters per minute on a DCS 1200 texturing machine. The primary heater ofthe texturing machine was 220° C., no secondary heater was used. Adraw-textured yarn of 78 decitex and 26 filaments (78f26) was preparedwith the texturing machine's 6 mm solid ceramic discs configured to1/7/1 smooth/working/smooth. The 78f26 yarns were circular knitted into28 gauge plain interlock fabrics, scoured, dyed and heat set. Fabricsamples of 300 mm by 25 mm were taken for water wicking tests. Thesesamples were hung vertically into a water bath and the vertical rise ofthe water was measured after two minutes. The mean of three samples isgiven in Table 2. The fabrics constructed from yarns having filaments ofthe preferred cross section showed a water wicking advantage overidentically constructed fabrics from yarns of circular filament crosssection. This advantage is at least a 2-fold improvement in waterwicking capability. TABLE 2 Vertical rise in Vertical rise in Texturedyarn used in mm (fabric in mm (fabric in circular knit longestdirection) shortest direction) 78f26 comparative circular 1.5 0 crosssection (Yarn 1C) false twist textured yarn 78f26 invention cross 3.72.7 section (Yarn 1A) false twist textured yarn

EXAMPLE 3

A drawn yarn of 192 decitex and 52 filaments was spun with the apparatusof FIG. 5 and using the spinneret plate with 52 capillaries of the crosssectional shape of FIG. 3 a. Nylon 66 polymer of 49.4 RV (by the formicacid method) was melted 10, extruded through a polymer filter pack 20and then through the above spinneret 30 maintained at a temperature of280° C. The extruded filaments 40 were cooled by a cross flow of air 50flowing at 0.4 meters per minute. The cross flow of air 50 was directedto first encounter confronting lobes 38 of the two segment capillaryshown in FIG. 3 a. The cooled filaments were converged into a yarnbundle 60 with oil and water application and forwarded along alternativePath A. The yarn was intermingled with an air jet 80, as typicallypractised in the art. The intermingled yarn 90 was then fed via feedroll 92 and associated separator roll (making several wraps on the rollto prevent slipping) to a second godet 94 and associated separator roll(the draw roll), moving at a surface speed 80% greater than that of thefeed roll 92. The intermingled yarn bundle 90 was drawn, by a totalfactor of 1.8, reducing the overall yarn titer. The drawn yarn 100 wastreated by a steam jet 110 to set the draw and to relax the yarn. Therelaxed yarn bundle 120 was passed through a second interlace jet 130and then the yarn 140 was wound up on a tube 150 at a speed of 3800meters per minute. This process provided cakes of fully drawn yarn (FDY)with a yarn linear density of 192 decitex, a breaking elongation of42.8%, tenacity of 41 cN/tex. The yarn in dry form had an RV of 50.3 bythe formic acid method. Filaments of this 52 filament yarn have a crosssectional shape normal to the longitudinal axis which is substantiallysimilar to those filaments shown in FIG. 4 a.

This yarn, Yarn 3A, was used as the weft yarn of a woven fabric of 3/1twill weave where the warp yarns were 78 decitex (51 circularfilaments). Weaving and fabric finishing details are given in Table 3.As a comparative example, a fully drawn yarn of 192 decitex and 52filaments was spun in exactly the same way as above but using aspinneret plate with “circular cross section” capillaries, this yarn wascalled Yarn 3B. A second fabric sample was woven using Yarn 3B in theweft as above. Weaving and fabric finishing details are given in Table3. The two fabrics were finished identically in greige, dyed andheat-set form. From each fabric specimen (greige, dyed and heat-set) 10samples of 75 square millimeters were cut. These samples were measuredfor fabric thickness in the same way using a micrometer. The results ofthe fabric thickness measurements (mean of 10 measurements) are providedin Table 3. The fabrics containing the preferred cross section filamentsin the weft were thicker than that woven of entirely circular crosssection filaments in the warp and weft. As a result, the woven fabricshaving the preferred cross section filaments in the weft provided alower density fabric with a lightweight aesthetic. TABLE 3 Greige GreigeDyed Dyed Heatset Heatset fabric fabric fabric fabric fabric fabric Yarn3B Yarn 3A Yarn 3B Yarn 3A Yarn 3B Yarn 3A Warp ends 57.5 × 38.8 58.2 ×39.7 61.3 × 40 62.2 × 39.8 61.5 × 41 61.6 × 41 per cm × weft picks percm Woven 0.22 0.24 0.20 0.22 0.20 0.21 fabric thickness millimeters

The above embodiments have been described by way of example only. Manyother embodiments of the filaments, yarns, spinnerets and processesaccording to the present invention will be apparent to the skilledreader.

1-38. (canceled)
 39. A process for making a polymer yarn comprising:extruding a polyamide melt through a spinneret; cooling the extrudedmelt in a cross flow of air to form solid filaments; optionally passingthe quenched filaments through a steam atmosphere, applying a fibrefinish oil; optionally interlacing the yarn, passing the yarn over feedroll and draw roll pair, said feed and draw rolls differing in surfacespeed by a fixed amount within the range of 10 to 100% of said feedroll; treating the draw yarn to reduce the final yarn shrinkage for goodyarn package formation; and optionally applying a fibre finish oil,interlacing the yarn and winding up the filaments at a speed greaterthan 3000 m/min, wherein the polymer yarn comprising at least a singleprofiled filament having an open hollow cross-sectional profile shapenormal to the longitudinal axis of the filament, said cross-sectionalprofile shape having a central arcuate portion and first and secondelongated leg portions, each of said leg portions having proximal anddistal end portions, said proximal end portions joining to said centralportion and said distal end portions joining to foot portions on eachleg portion, said foot portions having a dimension F, said leg portionsand said central arcuate portion defining an open portion, said legportions oriented in a substantially parallel relationship, and saidfoot portions defining an aperture leading to said open portion; saidaperture having a dimension D, wherein dimension D is less thandimension F, and wherein the profiled single filament linear density isless than 20 dtex and the yarn elongation to break is about 20 to 50%and the tenacity is about 25 to 60 cN/tex.
 40. A process for making apolymer yarn comprising: extruding a polyamide melt through a spinneret;cooling the extruded melt in a cross flow of air to form a solidfilament; optionally passing the quenched filaments through a steamatmosphere, applying a fibre finish oil; optionally passing the yarnover tension control rolls; and optionally interlacing the yarn andwinding up the filament at a speed greater than 3000 m/min, wherein thepolymer yarn comprising at least a single profiled filament having anopen hollow cross-sectional profile shape normal to the longitudinalaxis of the filament, said cross-sectional profile shape having acentral arcuate portion and first and second elongated leg portions,each of said leg portions having proximal and distal end portions, saidproximal end portions joining to said central portion and said distalend portions joining to foot portions on each leg portion, said footportions having a dimension F, said leg portions and said centralarcuate portion defining an open portion, said leg portions oriented ina substantially parallel relationship, and said foot portions definingan aperture leading to said open portion; said aperture having adimension D, wherein dimension D is less than dimension F, and whereinthe profiled single filament linear density is less than 20 dtex and theyarn elongation to break is about 55 to 85% and the tenacity is about 25to 40 cN/tex.